Data stored in the File format in Android [Android evolution thirty]

 

Previously, I briefly introduced two data storage methods, for example, Shared Preferences, in [Android evolution 14th], I wrote an example of the address book for storing data in the sqlite database. Next I will introduce the format of storing data in File. I will talk about two points in File format, files cannot be shared among different programs. Another feature is to use the openFileOutput method to open a file (create this file if the file does not exist). openFileOutput saves things to the file. I wrote an example: click the button and write a count of the int type in the file. divide it by 2 to get the remainder. If the remainder is 0, the status is off, if the remainder is 1, the status is on. The count value is always ++. This is a simple example. Reprinted please indicate the source: http://blog.csdn.net/wdaming1986/article/details/6849703

 

See: click the button and click the button again.

 

This is the content in the dmfile. cfg file: mButton always ++. If it is an odd number, mChange = false. If it is an even number, it is true.

 

 

Code: In this FileStorage project:

In the com.cn. daming package: Content in the FileStorageMainActivity. java class:

 

<Span style = "font-size: 13px; color: #000000;"> package com.cn. daming;

 

Import java. io. FileInputStream;

Import java. io. FileNotFoundException;

Import java. io. FileOutputStream;

Import java. io. IOException;

Import java. util. Properties;

 

Import android. app. Activity;

Import android. content. Context;

Import android. OS. Bundle;

Import android. view. KeyEvent;

Import android. view. View;

Import android. view. View. OnClickListener;

Import android. widget. Button;

Import android. widget. TextView;

Import android. widget. Toast;

 

Public class FileStorageMainActivity extends Activity {

Private TextView mTextView;

Private Button cButton;

Private boolean mChanged = false;

Public int mCount = 0;

@ Override

Public void onCreate (Bundle savedInstanceState ){

Super. onCreate (savedInstanceState );

SetContentView (R. layout. main );

MTextView = (TextView) findViewById (R. id. show_textview );

CButton = (Button) findViewById (R. id. button );

// Read the mChanged is true or false

ReadLoadFile ();

RefreTextView ();

InitButton ();

}

 

Private void initButton ()

{

CButton. setOnClickListener (new OnClickListener (){

Public void onClick (View arg0 ){

ReadLoadFile ();

If (mCount % 2 = 0)

{

MChanged = false;

RefreTextView ();

}

If (mCount % 2 = 1)

{

MChanged = true;

RefreTextView ();

}

MCount ++;

SaveFileStorage ();

}

});

}

 

Public void refreTextView ()

{

If (mChanged)

{

MTextView. setText ("the current status is: open! ");

}

Else

{

MTextView. setText ("the current status is off! ");

}

}

@ Override

Public boolean onKeyDown (int keyCode, KeyEvent event ){

If (keyCode = KeyEvent. KEYCODE_BACK)

{

// Save the fileStorage before the programe back

SaveFileStorage ();

If (mChanged)

{

Toast. makeText (this, "the exit state of the program is open! ", Toast. LENGTH_LONG). show ();

}

Else

{

Toast. makeText (this, "the exit status of the program is off! ", Toast. LENGTH_LONG). show ();

}

This. finish ();

Return true;

}

Return super. onKeyDown (keyCode, event );

}

Private void readLoadFile ()

{

// Make the Properties

Properties properties = new Properties ();

Try {

FileInputStream istream = this. openFileInput ("dmfile. cfg ");

Properties. load (istream );

}

Catch (FileNotFoundException e ){

Return;

}

Catch (IOException e ){

Return;

}

MChanged = Boolean. valueOf (properties. getProperty ("mChanging"). toString ());

MCount = Integer. valueOf (properties. getProperty ("mButton"). toString ());

}

Private boolean saveFileStorage ()

{

Properties properties = new Properties ();

Properties. put ("mChanging", String. valueOf (mChanged ));

Properties. put ("mButton", String. valueOf (mCount ));

Try {

FileOutputStream ostream = this. openFileOutput ("dmfile. cfg", Context. MODE_WORLD_WRITEABLE );

Properties. store (ostream ,"");

}

Catch (FileNotFoundException e)

{

Return false;

}

Catch (IOException e)

{

Return false;

}

Return true;

}

} </Span>

 

Content in the main. xml file:

 

 

<? Xml version = "1.0" encoding = "UTF-8"?>

<LinearLayout xmlns: android = "http://schemas.android.com/apk/res/android"

Android: orientation = "vertical"

Android: layout_width = "fill_parent"

Android: layout_height = "fill_parent"

>

<TextView

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content"

Android: text = "@ string/hello"

Android: gravity = "center_vertical | center_horizontal"

Android: layout_marginBottom = "15dip"

Android: layout_marginTop = "15dip"

/>

<Button

Android: id = "@ + id/button"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content"

Android: text = "test changing File content"

Android: layout_marginBottom = "10dip"

/>

<TextView

Android: id = "@ + id/show_textview"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content"

Android: gravity = "center"

/>

</LinearLayout>